These are illustrative figures to give a ball park estimate of costs and benefits. It’s important to have your particular property assessed for its suitability and to get an accurate estimate of costs and benefits.

Costs may vary according to the type of roof and its accessibility.

Benefits may vary according to the amount of usable, generally north facing, unshaded roof area.

As electricity prices increase, as they surely will, the capital value of energy efficient buildings will increase.

Overseas studies show that the increase in value can be roughly 15 times the annual electricity saving. For example if you are able to save $500 on your electricity bill you could add $7500 to the value of your home.

This trend is not yet fully evident in New Zealand but it’s reasonable to expect rising electricity prices will see New Zealand home values follow suit.

Certainly installing a solar hot water system will protect the investment in your home.

Of course annual savings and the annual return will increase as the price of electricity increases above today’s level. The chart shows the increase in average residential retail prices over the past 10 years ( about 8% p.a.) - we leave you to draw your own conclusions as to future increases.

How it all works

the basics

1Solarcollectors …

capture the energy of the sun and convert it into heat. There are two types of collectors: Flat Plate and Evacuated Tubes. In New Zealand’s climate they are about equally efficient and the choice comes down to durability, serviceability and aesthetical considerations.

We offer world leading Chromagen Flat Plate collectors.

Since these may be mounted at a tilt angle down to 20 deg they can be mounted parallel to many roofs, thereby providing good integration with the house.

2The hot water cylinder …

is possibly the most overlooked but most important system component.

It needs to be correctly sized to make the most of the hot water produced by the collector(s). Generally, a solar hot water cylinder should be larger than a standard hot water cylinder for the equivalent amount of hot water.

It also needs to be properly insulated. If the system is to be boosted by an electric element, this element needs to be correctly positioned within the cylinder.

For residential installations we offer Chromagen cylinders designed to match Chromagen solar collectors.

These cylinders come in two standard sizes: 200 & 300 litres.

If a solar hot water system is being retro-fitted, it is possible to use an existing hot water cylinder but it is almost always desirable to upgrade to a purpose-built cylinder in order to avoid compromising the system’s efficiencies.

The above components comprise a basic open loop Thermosiphon system. These systems have no moving parts, are easy to install, and in warmer climates are generally more efficient. However the water cylinder needs to be placed above the collector and this may not be desirable where a discreet installation is desired. Also, where the system is to be roof mounted it is important to ensure there is structural support for the weight of a full water tank.

Frost protection and water quality are important considerations.

beyond the basics

3The heat exchanger

Solar collectors, instead of heating water directly, heat a glycol/water mixture which passes through a heat exchanger in the hot water cylinder, thus heating your water indirectly.

This is a ‘closed loop’ system. There are two important benefits to a Closed Loop system:

-it protects your collector against the clogging that ‘hard’ water can cause and which reduces collector life as well as impairing its efficiency.

4The pump

Using a pump to circulate the liquid through the system creates a forced circulation system and allows the collector(s) and the hot water cylinder to be separated.

It also allows your collectors to work at a lower temperature.

5The controller …

keeps the whole system in balance by starting the pump when water in the collector is heated, turning on the booster when there is insufficient solar heat, and turning off the pump when the collector water is not hot enough.

There are times when there won’t be enough sunshine to heat as much hot water as you require. ‘Booster’ heating will then be needed to keep the hot water cylinder at the right temperature.

Typically the boost is provided by a heating element in the tank. It could also be provided by water externally heated by wetback or gas.

Open Loop, where the water is heated directly in the solar collectors, or

Closed Loop, where the water is heated indirectly via a heat exchanger, typically located in the hot water cylinder.

These systems may be thermosiphon, where no pump is required but the tank must be located above the solar collectors, or

They may be Forced Circulation, where a small pump is used to circulate the water or other heating liquid which in turn

enables the hot water cylinder to be located independently of the solar collectors, eg in a hall cupboard.

The solar collectors may be either Flat Plate or Evacuated Tubes.

As sunshine hours vary during the year, it is usually necessary to ‘boost’ the solar heating with another heat source,typically an electric element in the hot water cylinder.

Our Standard Chromagen systems are closed loop, forced circulation systems using flat plate solar collectors. We believe this configuration provides the best solution for most New Zealand conditions.

Chromagen is recognized as a world leader in solar hot water technology and we are confident that the components we offer rank with the best money can buy.

The value proposition

Costs

Prices range from $9800 for our smallest standard system, supplying about 120 litres of hot water per day, up to $10600 for a system that will supply about 150 litres per day.

(On average, 120 litres of hot water a day is sufficient for a family of three). Prices include GST.

These prices include standard installation costs within the Wellington region.

The prices for these systems include a hot water cylinder. This is a cost which you would have to pay anyway for a hot water cylinder when you buy a new house. Deducting the cost of the cylinder, net prices for our solar hot water systems range from $8000 to $8800.

The size of system best for you depends on:

•Your hot water usage

The more hot water you use the larger the system

•The amount of usable space on your roof

The smallest system requires 3 m2 ; the largest 5 m2

System efficiency improves with size as does the ‘comfort factor ‘of having a little bit more hot water, rather than a little bit less. Larger is better - always depending on your budget.

Benefits

Over a 12 month period an optimally sized system saves you about 75% of the electricity needed to heat water.

In the ‘average’ home, hot water accounts for about 30% of the electricity bill.

An average home in the Wellington region:

- an annual electricity bill of $2450 at today’s prices

- home to 2 adults and 1 child

- uses about 120 litres of hot water per day

Using the 75% of 30% guideline, potential annual savings for this household would be just over $550.

This example equates roughly to our mid-sized system, based on 2 Chromagen solar collectors and a 200 litre Chromagen hot water cylinder.

And, because the energy is in the form of heat, there is no financial exposure to changes in the price electricity retailers will buy back any exported electricity.